#include <stdio.h>
#include "aes.h"

static u8 pow_tab[256];
static u8 log_tab[256];
static u8 sbx_tab[256];
static u8 isb_tab[256];

static u32 rco_tab[10];
static u32 ft_tab[4][256];
static u32 it_tab[4][256];
static u32 fl_tab[4][256];
static u32 il_tab[4][256];

static __inline u8 byte(const u32 x ,const unsigned n)
{
    return x >> (n << 3);
}
static __inline u32 rol32(u32 word, unsigned int shift)
{
    return (word << shift) | (word >> (32 - shift));
}
static __inline u32 ror32(u32 word, unsigned int shift)
{
    return (word >> shift) | (word << (32 - shift));
}
static __inline u8 f_mult(u8 a , u8 b )
{
    u8 aa = log_tab[a];
    u8 cc = aa + log_tab[b];
    return pow_tab[cc + (cc < aa ? 1 : 0 )];
}
#define ff_mult(a,b) (a && b ? f_mult(a,b) : 0 )

#define f_rn(bo, bi, n, k)  \
bo[n] =  ft_tab[0][byte(bi[n],0)] ^   \
ft_tab[1][byte(bi[(n + 1) & 3],1)] ^  \
ft_tab[2][byte(bi[(n + 2) & 3],2)] ^   \
ft_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n) 

#define i_rn(bo, bi, n, k)                    \
    bo[n] =  it_tab[0][byte(bi[n],0)] ^                \
it_tab[1][byte(bi[(n + 3) & 3],1)] ^        \
it_tab[2][byte(bi[(n + 2) & 3],2)] ^        \
it_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)

#define ls_box(x)                \
    ( fl_tab[0][byte(x, 0)] ^            \
      fl_tab[1][byte(x, 1)] ^            \
      fl_tab[2][byte(x, 2)] ^            \
      fl_tab[3][byte(x, 3)] )

#define f_rl(bo, bi, n, k)                    \
    bo[n] =  fl_tab[0][byte(bi[n],0)] ^                \
fl_tab[1][byte(bi[(n + 1) & 3],1)] ^        \
fl_tab[2][byte(bi[(n + 2) & 3],2)] ^        \
fl_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)

#define i_rl(bo, bi, n, k)                    \
    bo[n] =  il_tab[0][byte(bi[n],0)] ^               \
il_tab[1][byte(bi[(n + 3) & 3],1)] ^        \
il_tab[2][byte(bi[(n + 2) & 3],2)] ^        \
il_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)

void gen_tabs (void)
{
    u32 i, t;
    u8 p, q;

    /* log and power tables for GF(2**8) finite field with
     *        0x011b as modular polynomial - the simplest primitive
     *               root is 0x03, used here to generate the tables */

    for (i = 0, p = 1; i < 256; ++i) {
        pow_tab[i] = (u8) p;
        log_tab[p] = (u8) i;

        p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0);
    }

    log_tab[1] = 0;

    for (i = 0, p = 1; i < 10; ++i) {
        rco_tab[i] = p;

        p = (p << 1) ^ (p & 0x80 ? 0x01b : 0);
    }

    for (i = 0; i < 256; ++i) {
        p = (i ? pow_tab[255 - log_tab[i]] : 0);
        q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2));
        p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2));
        sbx_tab[i] = p;
        isb_tab[p] = (u8) i;
    }

    for (i = 0; i < 256; ++i) {
        p = sbx_tab[i];

        t = p;
        fl_tab[0][i] = t;
        fl_tab[1][i] = rol32(t, 8);
        fl_tab[2][i] = rol32(t, 16);
        fl_tab[3][i] = rol32(t, 24);

        t = ((u32) ff_mult (2, p)) |
            ((u32) p << 8) |
            ((u32) p << 16) | ((u32) ff_mult (3, p) << 24);

        ft_tab[0][i] = t;
        ft_tab[1][i] = rol32(t, 8);
        ft_tab[2][i] = rol32(t, 16);
        ft_tab[3][i] = rol32(t, 24);

        p = isb_tab[i];

        t = p;
        il_tab[0][i] = t;
        il_tab[1][i] = rol32(t, 8);
        il_tab[2][i] = rol32(t, 16);
        il_tab[3][i] = rol32(t, 24);

        t = ((u32) ff_mult (14, p)) |
            ((u32) ff_mult (9, p) << 8) |
            ((u32) ff_mult (13, p) << 16) |
            ((u32) ff_mult (11, p) << 24);

        it_tab[0][i] = t;
        it_tab[1][i] = rol32(t, 8);
        it_tab[2][i] = rol32(t, 16);
        it_tab[3][i] = rol32(t, 24);
    }
}

#define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b)

#define imix_col(y,x)       \
    u   = star_x(x);        \
v   = star_x(u);        \
w   = star_x(v);        \
t   = w ^ (x);          \
(y)  = u ^ v ^ w;        \
(y) ^= ror32(u ^ t,  8) ^ \
ror32(v ^ t, 16) ^ \
ror32(t,24)

/* initialise the key schedule from the user supplied key */

#define loop4(i)                                    \
{   t = ror32(t,  8); t = ls_box(t) ^ rco_tab[i];    \
    t ^= E_KEY[4 * i];     E_KEY[4 * i + 4] = t;    \
    t ^= E_KEY[4 * i + 1]; E_KEY[4 * i + 5] = t;    \
    t ^= E_KEY[4 * i + 2]; E_KEY[4 * i + 6] = t;    \
    t ^= E_KEY[4 * i + 3]; E_KEY[4 * i + 7] = t;    \
}

#define loop6(i)                                    \
{   t = ror32(t,  8); t = ls_box(t) ^ rco_tab[i];    \
    t ^= E_KEY[6 * i];     E_KEY[6 * i + 6] = t;    \
    t ^= E_KEY[6 * i + 1]; E_KEY[6 * i + 7] = t;    \
    t ^= E_KEY[6 * i + 2]; E_KEY[6 * i + 8] = t;    \
    t ^= E_KEY[6 * i + 3]; E_KEY[6 * i + 9] = t;    \
    t ^= E_KEY[6 * i + 4]; E_KEY[6 * i + 10] = t;   \
    t ^= E_KEY[6 * i + 5]; E_KEY[6 * i + 11] = t;   \
}

#define loop8(i)                                    \
{   t = ror32(t,  8); ; t = ls_box(t) ^ rco_tab[i];  \
    t ^= E_KEY[8 * i];     E_KEY[8 * i + 8] = t;    \
    t ^= E_KEY[8 * i + 1]; E_KEY[8 * i + 9] = t;    \
    t ^= E_KEY[8 * i + 2]; E_KEY[8 * i + 10] = t;   \
    t ^= E_KEY[8 * i + 3]; E_KEY[8 * i + 11] = t;   \
    t  = E_KEY[8 * i + 4] ^ ls_box(t);    \
    E_KEY[8 * i + 12] = t;                \
    t ^= E_KEY[8 * i + 5]; E_KEY[8 * i + 13] = t;   \
    t ^= E_KEY[8 * i + 6]; E_KEY[8 * i + 14] = t;   \
    t ^= E_KEY[8 * i + 7]; E_KEY[8 * i + 15] = t;   \
}

int aes_set_key(struct aes_ctx * ctx, const u8 *in_key, unsigned int key_len)
{
    const __le32 *key = (const __le32 *)in_key;
    u32 i, t, u, v, w;

    if (key_len % 8 || key_len < AES_MIN_KEY_SIZE || key_len > AES_MAX_KEY_SIZE) {
        return -1;
    }

    ctx->key_length = key_len;

    E_KEY[0] = le32_to_cpu(key[0]);
    E_KEY[1] = le32_to_cpu(key[1]);
    E_KEY[2] = le32_to_cpu(key[2]);
    E_KEY[3] = le32_to_cpu(key[3]);

    switch (key_len) {
        case 16:
            t = E_KEY[3];
            for (i = 0; i < 10; ++i)
                loop4 (i);
            break;

        case 24:
            E_KEY[4] = le32_to_cpu(key[4]);
            t = E_KEY[5] = le32_to_cpu(key[5]);
            for (i = 0; i < 8; ++i)
                loop6 (i);
            break;

        case 32:
            E_KEY[4] = le32_to_cpu(key[4]);
            E_KEY[5] = le32_to_cpu(key[5]);
            E_KEY[6] = le32_to_cpu(key[6]);
            t = E_KEY[7] = le32_to_cpu(key[7]);
            for (i = 0; i < 7; ++i)
                loop8 (i);
            break;
    }

    D_KEY[0] = E_KEY[0];
    D_KEY[1] = E_KEY[1];
    D_KEY[2] = E_KEY[2];
    D_KEY[3] = E_KEY[3];

    for (i = 4; i < key_len + 24; ++i) {
        imix_col (D_KEY[i], E_KEY[i]);
    }

    return 0;
}

/* encrypt a block of text */

#define f_nround(bo, bi, k) \
    f_rn(bo, bi, 0, k);     \
f_rn(bo, bi, 1, k);     \
f_rn(bo, bi, 2, k);     \
f_rn(bo, bi, 3, k);     \
k += 4

#define f_lround(bo, bi, k) \
    f_rl(bo, bi, 0, k);     \
f_rl(bo, bi, 1, k);     \
f_rl(bo, bi, 2, k);     \
f_rl(bo, bi, 3, k)

void aes_encrypt(struct aes_ctx * ctx, u8 *out, const u8 *in)
{
    const __le32 *src = (const __le32 *)in;
    __le32 *dst = (__le32 *)out;
    u32 b0[4], b1[4];
    const u32 *kp = E_KEY + 4;

    b0[0] = le32_to_cpu(src[0]) ^ E_KEY[0];
    b0[1] = le32_to_cpu(src[1]) ^ E_KEY[1];
    b0[2] = le32_to_cpu(src[2]) ^ E_KEY[2];
    b0[3] = le32_to_cpu(src[3]) ^ E_KEY[3];

    if (ctx->key_length > 24) {
        f_nround (b1, b0, kp);
        f_nround (b0, b1, kp);
    }

    if (ctx->key_length > 16) {
        f_nround (b1, b0, kp);
        f_nround (b0, b1, kp);
    }

    f_nround (b1, b0, kp);
    f_nround (b0, b1, kp);
    f_nround (b1, b0, kp);
    f_nround (b0, b1, kp);
    f_nround (b1, b0, kp);
    f_nround (b0, b1, kp);
    f_nround (b1, b0, kp);
    f_nround (b0, b1, kp);
    f_nround (b1, b0, kp);
    f_lround (b0, b1, kp);

    dst[0] = cpu_to_le32(b0[0]);
    dst[1] = cpu_to_le32(b0[1]);
    dst[2] = cpu_to_le32(b0[2]);
    dst[3] = cpu_to_le32(b0[3]);
}

/* decrypt a block of text */

#define i_nround(bo, bi, k) \
    i_rn(bo, bi, 0, k);     \
i_rn(bo, bi, 1, k);     \
i_rn(bo, bi, 2, k);     \
i_rn(bo, bi, 3, k);     \
k -= 4

#define i_lround(bo, bi, k) \
    i_rl(bo, bi, 0, k);     \
i_rl(bo, bi, 1, k);     \
i_rl(bo, bi, 2, k);     \
i_rl(bo, bi, 3, k)

void aes_decrypt(struct aes_ctx * ctx, u8 *out, const u8 *in)
{
    const __le32 *src = (const __le32 *)in;
    __le32 *dst = (__le32 *)out;
    u32 b0[4], b1[4];
    const int key_len = ctx->key_length;
    const u32 *kp = D_KEY + key_len + 20;

    b0[0] = le32_to_cpu(src[0]) ^ E_KEY[key_len + 24];
    b0[1] = le32_to_cpu(src[1]) ^ E_KEY[key_len + 25];
    b0[2] = le32_to_cpu(src[2]) ^ E_KEY[key_len + 26];
    b0[3] = le32_to_cpu(src[3]) ^ E_KEY[key_len + 27];

    if (key_len > 24) {
        i_nround (b1, b0, kp);
        i_nround (b0, b1, kp);
    }

    if (key_len > 16) {
        i_nround (b1, b0, kp);
        i_nround (b0, b1, kp);
    }

    i_nround (b1, b0, kp);
    i_nround (b0, b1, kp);
    i_nround (b1, b0, kp);
    i_nround (b0, b1, kp);
    i_nround (b1, b0, kp);
    i_nround (b0, b1, kp);
    i_nround (b1, b0, kp);
    i_nround (b0, b1, kp);
    i_nround (b1, b0, kp);
    i_lround (b0, b1, kp);

    dst[0] = cpu_to_le32(b0[0]);
    dst[1] = cpu_to_le32(b0[1]);
    dst[2] = cpu_to_le32(b0[2]);
    dst[3] = cpu_to_le32(b0[3]);
}
